Add forbid-in-block-sequences feature for detecting empty values in block sequences

[ericalmeidasp]

feat: Add forbid-in-list-items feature to detect empty values in lists

This commit introduces a new feature, forbid-in-list-items, which allows users to check for empty values within lists. The default behavior is set to false, but it can be activated by setting the forbid-in-list-items configuration variable to true.

The check function has been updated to handle this feature, and it will now identify and report empty values within list items when forbid-in-list-items is enabled.

This enhancement provides users with more control and flexibility when using the linter for YAML files.

[coveralls]

coverage: 99.396% (+0.005%) from 99.391%
when pulling 62f54e2 on ericalmeidasp:master
into e1d45c3 on adrienverge:master.

[adrienverge]

Hello Éric, and thanks for contributing to yamllint!

For consistency with YAML vocabulary and already-existing yamllint options forbid-in-block-mappings and forbid-in-flow-mappings, this new feature should be named forbid-in-block-sequences (and a new option forbid-in-flow-sequences shouldn't be necessary because I believe [1, , 3] is invalid YAML syntax). Same for the documentation paragraph, the LintProblem message and test functions names.

Since the rule empty-values is disabled in default and relaxed configurations, I would set this option enabled by default, like forbid-in-block-mappings and forbid-in-flow-mappings are. It will create new errors or warnings for some users with specific configurations, but it's easy to fix. What do you think?

[ericalmeidasp]

Hello! Thank you so much for the code review,

In response to the valuable feedback provided, I have made the following changes:

1. Renamed the feature from forbid-in-list-items to forbid-in-block-sequences.

2. Updated the documentation paragraph, LintProblem message, and test function names to align with the new feature name.

3. Set the forbid-in-block-sequences option to be enabled by default, similar to forbid-in-block-mappings and forbid-in-flow-mappings. I agree with u, adjusted to maintain consistency.

In addition to these changes, I've also added more test cases to cover various scenarios. However, due to the forbid-in-block-sequences option being set as the default, I had to modify the existing test cases by including forbid-in-block-sequences: false to avoid interference with the existing test scenarios in the test_empty_values.py file.

Thanks!

[adrienverge]

This looks perfect, thank you! I'm merging this so it goes in the next yamllint release.

⚠️ To all yamllint users: this is a BREAKING CHANGE if the empty-values rule is enabled in your configuration. But if it's the case, you probably want this new option forbid-in-block-sequences enabled too, for consistency. In case you want to disable it, just use this configuration in your .yamllint:

rules:
  empty-values:
    forbid-in-block-mappings: true
    forbid-in-flow-mappings: true
    forbid-in-block-sequences: false